Dasher Bullet Seating Depth?

[Skeeter]

Now that I have my brass formed I was looking for some advise on a seating depth for the Dasher. The bullets I am going to be testing are the following.

Berger 80gr
Berger 88gr LD
Combined Tech 95gr Ballistic Tip
Berger 95gr VLD

Just not sure if the Dasher likes them seated into the lands or jumped. Thanks

Skeeter

 

[Skeeter]

dmoran,

If you seat them right at the lands, how far into the neck do you think the bullet seats? When testing a few of the VDL's to get the bullet right at the lands, the base of the bullet would be right at or below the shoulder junction of the case.

Does anyone have an OACL to the ogive for VLD's as well? Thanks

 

[expiper]

Yur chamber is allready cut....the dims from someone elses chamber will not match yours....you gotta make em fit your gun...Just jam-em and then work your way bak to see what is best with your particular powder/primer/chamber/bbl twist-groove depth/etc/etc....Roger

 

[Skeeter]

Took some measurements and found that with my chamber dimensions a formed case with a 95gn VLD seat at 2.760" to the lands. On 88gn LD's they seat at 2.773"

Skeet

 

[expiper]

Hi Skeeter...are those dims. over some sorta measuring device.????,stony point-etc.).!!!????? They must be....mine are aprox .3 inches shorter...measuring just to the tip of the respective bullet....the main thing is how much shank do you have in the case...and are they above the donut....sounds like you are ready to go shootin...great........Roger

 

[Skeeter]

expiper.

Yes, I took the measurements using a Stoney Point guide and insert.

I checked the seating depth by coloring a bullet with a sharpie then inserting it into the case. When pulled the bullet shows the seating depth by removing the color from the bullet by the case mouth as it's inserted.

I am good on the depth as I have about 30% of the neck remaining before the dough nut area on the VLD's and about 40% with the 88gr LD's

Skeet

 

[Forum Boss]

You'll need to measure the distance to the lands with each bullet. Since there are variances from one particular bullet to the next, I suggest measuring 3-4 bullets of each type to give you a "zero" length.

Another thing to keep in mind with the Hornady/Stoney Pt tool, if this is a NEW unfired barrel. I've seen the distance to the lands move .020 or more after, say, 25 shots, but then it gets rock stable. What's going on is that a little ridge or machining mark on a land gets ironed out.

This may or may not happen with your barrel. I would just re-measure everything after 50 rounds through the tube.

Sounds like you have a pretty long throat for some of these bullets. Not a problem, but you may want jumping some of the bullets. For the jump measures I like to start .020 out and work in.

Otherwise I recommend .015" into the lands and work back in small increments.

Each bullet may have a different preference so that's why we keep log-books!

 

[Skeeter]

Ok,

I have just spent about 2 hours trying to figure out the appropriate seating depth for my bullets and chamber. No matter how much I back off the die so that the bullet does not exceed the .250 neck length,and into the doughnut area), when I chamber the round it seats the bullet back further into the case exceeding the neck length. Below is a chart I used to get my bullet seating depth based on dmoran suggestions.

Can someone look at my data below and let me know what I am missing here. Thanks

Skeet

 

[Skeeter]

Dmoran

I know what you mean. All 300 cases I fire formed come up exactly the same short length. All of them started as Lapua 6BR at 1.550 and after fire forming ended up at 1.500,.050 shorter).

All brass was fire formed using COW method,necked up with .257 and down with .267 to false shoulder), 8.5 grains of Titewad, tissue then filled with COW and tissue wad to hold COW in, CCI 500 primer and shot in a separate barrel not to ruin my good Krieger.

Both barrels were reamed using the same reamer. Attached is the reamer drawing from Dave Kiff.

I just remeasured all of the info on the cases and I had an extra digit in the OAL that caused 2 of the numbers to be transposed. I corrected them but the average case length is still 1.504",none of those in the table have been shot at full dasher loads yet)

I also remeasured the neck length and appears to measures .250 but is really difficult for me to get exact measurement.

I was hoping the short length had something to do with COW fire forming and that it will lengthen once fired a few times at full load? The ones I fired at full dasher load on Thursday, measure 1.545 but I only shot about 20, so I don't have a lot of them to go by yet.

Skeeter

 

[Skeeter]

Everyone....I was totally freaked out by the measurements and the responses I received that I decided to call my smith this morning and he had me bring everything over to his shop.

As it turns out, he measured all my brass and it measures between 1.550 and 1.553,including the COW brass).... appears my calipers are totally screwed up and all over the map with regards to measurements.

He ordered me a new set of Mitutoyo digital calipers to use and so I am pitching my old set. I will hold off on any additional loading until my new set arrives.

Therefore, please disregard all my previous measurements until I get my new calipers to start over with.

Thanks again for all the advise and dmoran especially as he had me so worried it caused me to call my smith to straighten it out.

Skeeter